In a normal field of vision, humans have two eyes that perceive images which the eyes view from two different viewpoints, respectively, due to their spatial separation of the eyes in the head. Parallax of the two images allows the humans brain to recognize the images from the two different viewpoints as a stereoscopic image. By utilizing this principle, there has been developed a liquid crystal display which causes an observer to view and recognize images from two different viewpoints through the right eye and the left eye, respectively, so as to generate parallax, thereby providing a 3D (three-dimensional) display.
In a conventional 3D liquid crystal display, images from respective different viewpoints are supplied to the right and left eyes of the observer, by first encoding the left eye image and right eye image on a display screen according to e.g. color, polarization state, or display time, and then separating these images through a filter system of glasses worn by the observer. The filter system allows the left eye image and the right eye image which have been separated to be supplied to the left eye and the right eye of the observer, respectively.
In another liquid crystal display, as illustrated in FIG. 8(a), a display panel 101 is combined with a parallax barrier 102 having light-transmitting regions and light-shielding regions arranged in a stripe pattern. This allows an observer to recognize a 3D image without using a visual assistance such as a filtering system (autostereoscopic display). Specifically, a parallax barrier 102 gives specific viewing angles to a right eye image and a left eye image generated by the display panel 101. When viewed in a specific spatial viewing region, the right eye image and the left eye image are viewed and recognized by the right eye and the left eye, respectively, so that a 3D image is recognized by the observer (see FIG. 8(b)).
Further, by employing the same technique used in the 3D display, it is possible to realize a display apparatus in which, when a single display screen image is viewed from different directions, i.e., the left and right directions, different images are displayed on the display screen for the respective directions in which the display screen image is viewed and recognized. Specifically, by displaying images separated by a parallax barrier as different individual images, not as the right eye image and the left eye image in a 3D display, it is possible to supply different images to a plurality of observers who view the single display image from the left and right directions.
Japanese Unexamined Patent Publication, No. 110495/1996 (Tokukaihei 8-110495, publication date: Apr. 30, 1996) describes a crosstalk issue in a 3D display apparatus employing a liquid crystal panel and a parallax barrier. That is, this publication discloses that, according to a 3D display apparatus, a stereoscopic vision cannot be realized, because there is a region where both of a right eye image and a left eye image are observed by a single eye. Such overlapping of the right eye image and the left eye image is called as crosstalk.
However, according to the publication Tokukaihei 8-110495, crosstalk in the 3D display apparatus is determined depending on an aperture ratio of an aperture section of the parallax barrier, and it is understood that no crosstalk occurs at an optimum viewing position.
Further, the aforementioned 3D display apparatus and the display apparatus which supplies different images to respective observers employ display-use liquid crystal panels, which basically have a same structure. In each of the display-use liquid crystal panels, each pixel pattern includes TFT devices and transparent pixel electrodes, for example. Further, each of the pixel patterns is disposed, in a matrix manner, at each intersection of a gate line and a source line. The gate lines and the source lines are isolated by an interlayer insulating film interposed in between.
In such a liquid crystal display panel, normally, there is not sufficient liquid crystal capacitance between a pixel electrode and an opposing electrode. Therefore, an auxiliary capacity line is provided in parallel to a gate line. When extending a drain electrode of a TFT device up to the auxiliary capacity line, a section in which the drain electrode and the auxiliary capacity line are superimposed is formed. This allows an auxiliary capacitor (an electric charge holding capacitor) to be formed between the drain electrode and the auxiliary capacity line in the superimposed section. An insulating layer between the drain electrode and the auxiliary capacity line in the superimposed section acts as an insulating material.
However, inventors of the present invention have found that when the conventional liquid crystal panel is used in a 3D display apparatus or the like, crosstalk occurs even in the optimum viewing position, where no crosstalk is supposed to occur according to the publication Tokukaihei 8-110495. This causes display performance to be degraded due to the crosstalk.
That is, in each of the pixel patterns on the liquid crystal display panel, an aperture section, i.e., a light-transmitting region, will not be in a simple rectangular shape due to positions of the disposed TFT devices and/or auxiliary capacitors, or other factors. In this case, the aperture section may partially have a narrow gap due to positions or shapes of the disposed TFT devices or auxiliary capacitors, or other factors.
When the light passes through small aperture sections with a regular interval, the light has a characteristic causing its propagation direction to curve (i.e., diffraction phenomenon). As such, when a pixel pattern includes such aperture sections having a narrow gap, light passing through the aperture sections causes a diffraction phenomenon.
On this account, as illustrated in FIG. 9, in a 3D display apparatus in which a parallax barrier and a display-use liquid crystal panel are combined, for example, in cases where light causes the diffraction phenomenon during a period in which the light, to which a specific viewing angle is given, passes through the parallax barrier, it becomes impossible to completely separate the light into “light for the left eye” and “light for the right eye”. This would give rise to the problem that an optical crosstalk occurs and a 3D display performance is degraded.
Specifically, when the light is diffracted as it passes through the aperture sections having a narrow gap (indicated by bold lines in FIG. 9), in addition to the light to which a specific viewing angle is given as it passes through the parallax barrier, the light thus diffracted causes to serve to supply the left eye image and the right eye image to the right eye and the left eye of the observer, respectively (in this specification, such optical behavior is referred to as crosstalk). The crosstalk behavior causes an image to be appeared as a blurred image during 3D display. Note that, the similar problem occurs during a display in which different images are supplied to a plurality of observers. In this case, the observers perceive an image in which one display image overlaps another display image.
The crosstalk due to the diffraction phenomenon is not an inherent problem in a parallax barrier system, but occurs in other systems such as systems using lens arrays or glasses. Further, the crosstalk occurs not only in a system where a display image is separated according to a plurality of viewpoints at one time, but also in a system where a display image is separated according to a plurality of viewpoints in a time division manner.